Off-site construction is an approach to construction projects that seeks to move the construction process away from site and take advantage of efficiencies from manufacturing approaches and standardisation. Off-site construction is portrayed as having the potential to improve the performance of the construction industry and deliver benefits on projects such as better predictability of cost and time, better quality construction, improved health and safety and faster construction programme. However, there is minimal objective evidence-based research that quantifies these benefits in a consistent manner, with many studies and reports noting perceived benefits or opinions of stakeholders. This report identifies specific metrics and methods for quantifying project performance and outcomes that may be influenced by adopting off-site construction, with a focus on buildings projects. For each metric, the boundaries of measurement are defined to ensure consistent and comparable results across projects. The reader is guided through the process of identifying metrics for assessment and how these are expected to be influenced by off-site construction in the academic and industry literature. The methodology is tested through the analysis of project data received on case study projects in the educational sector, demonstrating for readers how the metrics could be used to assess project performance. The methodology provides a template for evaluating project performance that can be used by clients and construction management teams to assess the value and benefits achieved on projects. This could be applied across different building sectors in the construction industry and be adapted to be suitable for infrastructure projects.